Hydrogel fracture experiment: from different stimuli to delayed fracture study (B)

• Main Author: Ng, Julius Yi Qin
• Other Authors: Li Hua
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/168276
• Institution: Nanyang Technological University

Hydrogels are 3D network structures that can absorb considerable amount of water without dissolving due to cross-links or chain entanglements. They can exist naturally, such as in collagen, which is a form of polymer, or can be made synthetically. To be classified as a hydrogel, water must make up at least 10% of the total volume. There are various types of hydrogels and ionic hydrogels are something new that has not been explored much yet. Diving deeper into ionic hydrogels, there are also multiple ways to ionize the different types of hydrogels. One of the methods would be to use metal ion-containing solutions which are known as ionic compounds as well. For this report, NaCl, known as salt, will be used to ionize PAAm hydrogels to obtain ionized acrylamide hydrogel. As hydrogels absorbs solution well, it will be expected that hydrogels will swell when ionizing them. To expand the use of ionized hydrogels, multiple experiments are conducted to test their strength and durability. For this report, it will explore how the different salt concentrations affect the strength and elasticity of ionized acrylamide hydrogel through tensile and delayed fracture. It will also explore how the hydrogel swells in different salt concentration and calculate the energy release rate.